The role of South Pacific dust provenance changes in Pliocene-Pleistocene climate variability (IODP Expedition 383)

矿物尘是地球气候系统的重要组成部分。据推测，增加空气中的铁（Fe）供应到铁缺乏的南大洋促进初级生产力，导致大气CO2的净下降。这种重要的反馈机制被认为迫使气候系统在晚更新世期间走向完全的冰川状态。同样，南大洋的灰尘-铁反馈已被认为是解释冷却趋势的中更新世冰期和上新世晚期的北方半球冰期的开始。南太平洋最近的研究表明，南大洋的灰尘-铁反馈与来自特定南半球源区的灰尘排放及其与主要西风的输送密切相关。特别是，环极输送的灰尘从中南美洲的来源起着主导作用的尘埃沉积在南太平洋的亚季风区（SAZ）。澳大利亚和新西兰的灰尘输入是整体次要的，但他们的贡献增加在冰川周期的后期阶段。该项目的目的是建立在这些最新的研究结果和调查的作用，在南太平洋尘埃来源的变化在过去5马的气候变化，使用海洋沉积物IODP远征383站点U1540和U1541。将从样品中提取尘埃部分，并分析其地球化学指纹（稀土元素，铅，钕和锶同位素）。贝叶斯混合模型的源解析将量化每个样本中不同潜在源区的贡献。这些数据将被用来确定传输路径和机制的灰尘交付到研究区域在过去的5马。国家和国际项目合作伙伴使用相同的沉积物岩心分析补充参数，包括颗粒通量和尘埃粒度测量。这些数据集的组合将首次提供南半球尘埃循环变化及其在上新世-更新世气候变化中的作用的全面图片。

Mineral dust is an important component of the Earth’s climate system. It has been hypothesized that the increase in airborne iron (Fe) supply to the Fe-deficient Southern Ocean promoted primary productivity resulting in a net drawdown of atmospheric CO2. This important feedback mechanism was suggested to have forced the climate system towards full glacial states during the Late Pleistocene. Similarly, the Southern Ocean dust-Fe feedback has been considered to explain the cooling trends of mid-Pleistocene glacial intervals and during the late Pliocene onset of the Northern Hemisphere Glaciation. Recent work from the South Pacific showed that the Southern Ocean dust-Fe feedback is critically linked with dust emissions from specific Southern Hemisphere source regions and their transport with the predominant westerly winds. In particular, the circumpolar transport of dust from Central South American sources plays a dominant role for the dust deposition in the Subantarctic Zone (SAZ) of the South Pacific. Australian and New Zealand dust input is overall secondary, but their contributions increase during the later stages of glacial cycles. This project is designed to build upon these recent findings and investigate the role of changes in South Pacific dust provenance in the climate variability of the last 5 Ma using marine sediments from IODP Expedition 383 sites U1540 and U1541. The dust fractions will be extracted from the samples and analyzed for their geochemical fingerprint (rare earth elements, and lead, neodymium, and strontium isotopes). Source apportionment with Bayesian mixing models will quantify the contributions from the different potential source areas in every individual sample. These data will be used to identify transport routes and mechanisms of dust delivered to the study area during the last 5 Ma. The same sediment cores are used by national and international project partners to analyze complementary parameters including particle flux and dust grain size measurements. The combination of these datasets will provide, for the first time, a comprehensive picture Southern Hemisphere dust cycle changes and their role in Pliocene-Pleistocene climate variations.